This invention relates to microwave structures for the transmission of electromagnetic waves in different modes of propagation and, more particularly, to a structure enabling the coupling of waves at differing polarizations into a wide bandwidth transmission link.
Various types of microwave systems employ the transmission of microwave signals having different polarizations in a common waveguide. By way of example, a radar system may employ a horn fed by a waveguide carrying cross-polarized electromagnetic waves for driving the horn in two orthogonal modes. A structure which has been used for combining the electromagnetic waves is the orthogonal mode tee having both an E-plane bend and an H-plane bend whereby waves having cross polarization can be launched in a single waveguide structure.
A problem arises in that presently available microwave structures are excessively limited in bandwidth so that, as a practical matter, only two signals can be transmitted in the orthogonal mode configuration. The use of plural frequencies in each mode of transmission has not been attainable due to the limited bandwidth of microwave structures which couple signals of differing polarizations into a common waveguide transmission link. As a result, designers of microwave signal transmission systems, such as radar systems, are unduly limited in the number of microwave channels which can be carried in a single waveguide transmission link.